To such automobiles or fright cars various types of electric devices composing air conditioners, wipers, or power windows are mounted. These electric devices are electrically connected with electric control units (ECU) composed of such computers, and from or to these electric devices and the ECUs electric powers or control signals are transmitted.
Conventionally, as electric control system controlling the aforementioned electric devices, for example, what is as shown in FIG. 7 is advocated (such as PTL 1). As shown in the figure, the electric control system 1 is provided with a single ECU 2, and a plurality of relay connectors 33 as communication device, a not-shown plurality of electric devices each connected to the relay connector 33. These ECU 2 and relay connectors 33 are commonly connected to one second wire harness 22.
The second wire harness 32 is composed of three lines of a electric power line L1, a ground line L2, and a signal line L3. The EUC 2 and the plurality of relay connectors 33 are commonly connected to the electric power line L1, the ground line L2, and the signal line L3.
The aforementioned relay connectors 32 communicate with the EUC 3 via the signal line L3, and controls a not-shown electric device connected with the relay connector based on the communication. Note that in the relay connectors 33 not-shown CPUs are each incorporated that wholly controls the relay connectors 33.
Thus, in order to connect the one signal line L3 to the ECU 2 and the relay connectors 33 to communicate, ID is set to each relay connector 33 as an identification data. And the relay connector 33 each transmits the signal accompanied with the IDs of a source and itself and receives the signal accompanied with its own ID.
No set of the aforementioned ID disables communication with the ECU 2 and the plurality of relay connector 33 connected with the one signal line L1, and thus it is indispensable to set the IDs. conventionally, as such set of the aforementioned IDs, for example, in the housing of the relay connector 33 a plurality of ID setting switches is mounted, or in not-shown non-volatile memory disposed in the relay connector 33 each ID is stored upon manufacturing.
Disadvantageously, a method of the aforementioned setting of ID requires product management every ID. Furthermore, the same appearance results in misconnection because of indiscrimination of the relay connector 33 from each other and uncontrollability, and may cause product defects. It is then, for example, conceivable to make the relay connector 33 such configuration as shown in FIG. 8A. The relay connector 33 is provided with a circuit board 33c, a connector 33d mounted on the circuit board 33c, and a IC chip 33e mounted on the circuit board 33c and having a CPU incorporated therein.
This IC chip 33e is supposed to be provided with a plurality of ID setting terminals 33f other than a terminal for communication or supplying power, and as shown in FIGS. 8B and 8C, changing of the number or position between the ID setting terminals 33f and wiring 33g of ground or power source is supposed to allow the ID to be set. In this case, observation of pattern of wiring 33g can discriminate the relay connectors 33 from each other, there is required that the circuit boards 33c of which pattern is different every ID are each prepared, and thereby the problem has not yet been resolved that product management is required every ID.